Title of Invention	"A METHOD TO PRODUCE SURFACE-COATED STEEL SHEET FOR BATTERY CONTEINER"
Abstract	The object is to provide a surface-treatment steel plate for a battery case which has excellent forming properties and contributes to enhancing the battery performance and its manufacturing method and, further to manufacture a battery case made of the surface-treatment steel plate efficiently at a low cost. A steel plate is subjected to degreasing, pickling and plating, or to degreasing, pickling, plating and heat treatment. The surface-treated steel plate is heated to a temperature about Tm to Tm+100°C (Tm is the melting point of petroleum wax lubricant which is to be applied to the steel plate) and the melted lubricant is applied to the surface of the heated steel plate- The surface-treated steel plate is formed into a battery case by a deep-drawing process, a DI process for a DS process and then the formed battery case is subjected to a heat treatment at a low temperature of 200-350°C.

Title of Invention

"A METHOD TO PRODUCE SURFACE-COATED STEEL SHEET FOR BATTERY CONTEINER"

Abstract

The object is to provide a surface-treatment steel plate for a battery case which has excellent forming properties and contributes to enhancing the battery performance and its manufacturing method and, further to manufacture a battery case made of the surface-treatment steel plate efficiently at a low cost. A steel plate is subjected to degreasing, pickling and plating, or to degreasing, pickling, plating and heat treatment. The surface-treated steel plate is heated to a temperature about Tm to Tm+100°C (Tm is the melting point of petroleum wax lubricant which is to be applied to the steel plate) and the melted lubricant is applied to the surface of the heated steel plate- The surface-treated steel plate is formed into a battery case by a deep-drawing process, a DI process for a DS process and then the formed battery case is subjected to a heat treatment at a low temperature of 200-350°C.

Full Text	Specification (Field of the invention) The present invention relates to the surface-treated steel sheet for a battery container, production method thereof, a battery container utilizing said surf ace-treated steel sheet and manufacturing method thereof, and a battery utilizing said battery container. In more details, the invention relates to the surface-treated steel sheet suitable for a battery container and production method thereof, and a battery container manufactured from said surface-treated steel sheet and manufacturing method thereof, a battery using said surface-treated steel sheet, in which a cylindrical container having an integrated bottom portion and wall portion formed by a severe forming process such as deep drawing, drawing and ironing (hereinafter called DI process), or drawing and stretch forming (hereinafter called DS process). (Prior Art) It has become a main stream in recent years to manufacture a battery container using deep drawing the surface-treated steel sheet after being nickel plated or heat treated after plating as a battery container manufacturing method in which strong alkali solution is packed for use in alkali-manganese battery or nickel cadmium battery, instead of the conventional barrel plating method after deep drawing a steel sheet into a battery container. Especially, the DI process has recently been used for the manufacture of battery containers in view of increasing battery capacity, material cost reduction by reducing the wall thickness and also the further improvement of battery capacity. In view of similar points as mentioned above, the manufacturing method using the DS process has also been studied. The spread of these battery container manufacturing methods has resulted in the increasing demand for battery container materials having not only excellent battery performance but also excellent formability. Generally, in the battery container manufacturing, it has been a common practice to coat a lubricant on battery container material such as nickel plated steel sheets prior to the forming process such as additional drawing, and then the lubricant is removed by degreasing and rinsing after the forming process, and then dried. (Objective of the present invention) The conventional battery container manufacturing methods as explained above require such extremely troublesome operations to uniformly coat a lubricant on battery container materials just prior to press forming, or to drip a lubricant while press forming. Moreover, it is inevitably required to carry out two additional processes after the forming process for a battery container; namely, removal of lubricant by degreasing-rinsing and drying after rinsing. As explained above, the conventional battery container manufac- turing methods have been extremely unsatisfactory in view of elimination of labor, water resources and thermal energy consumption. The present invention will allow to solve all these problems at the same time, and the objective is to provide a surface-treated steel sheet for a battery container which is excellent in battery performance and formability and production method thereof, battery container made of said surface-treated steel sheet and manufacturing method thereof, and a battery using said battery container. (Means to solve the problem) The present invention for the surface-treated steel sheet for a battery container is characterized in that a petroleum wax type lubricant is coated on the surface- treated layer, after the steel sheet is degreased and pickled, and then plated, or further heat treated after plated. It is preferable that the surface-treated layer should have mono layer or a multiple layer consisting one layer or more than two layers including any one of nickel layer, nickel-phosphorus alloy layer, nickel-iron alloy layer, nickel-tin alloy layer, nickel-phosphorus-tin layer, or nickel-tin-iron alloy layer, and it is also preferable that the surf ace-treated layer should contain 1 to 45kg/m2 of nickel. It is also characterized in that the surface-treated layer is a mono layer or a multiple layer consisting of one or more than two types of layers including nickel-tin-alloy layer, nickel-phosphorus-tin alloy layer, or nickel-tin-iron alloy layer, with the tin content in the ratio of not more than 0.67 (by weight-ratio to the plating weight of nickel). Furthermore, it is characterized in that said petroleum wax type lubricant consists of any one of paraffin wax, micro crystalline wax, fluid paraffin, petrolatum, white petrolatum, polyethylene wax, polypropylene wax, ethylene-propylene wax, and it is also characterized in that the coating weight of said petroleum wax type lubricant should be 200 to 2000 mg/m2. The present invention is also characterized by the production method for the surface-treated steel sheet which is plated after de-greasing and pickling, or heat treated after plating to form a surface-treated layer, and then heated to the melting temperature of the petroleum wax type lubricant (Tm) to Tm +100 ° C and coated with a thermally molten petroleum wax type lubricant on its surface. It is characterized in that the steel sheet is plated with nickel or nickel-phosphorus alloy after degreasing and pickling the steel sheet, or it is further heat treated in a non-oxidizing atmosphere after nickel plating or nickel-phosphorus alloy plating, and it is also characterized in that the steel sheet is plated with nickel or nickel-phosphorus alloy, and then it is further plated with tin on it, and then heat-treated in the air or non-oxidizing atmosphere. And it is characterized that the surface-treated steel sheet is coated with 200 to 2000 mg/m 2 of said petroleum wax type lubricant. In addition, the manufacturing method for a battery container of the present invention is characterized in that this cylindrical bat- tery container having an integrated bottom portion and wall portion is heat-treated at 200 to 350°C for 3 to 30 minutes, after the surface-treated steel sheet is formed into a cylindrical battery container having an integrated bottom portion and wall portion by deep drawing, ironing after deep drawing, stretch forming after deep drawing, and the present invention also covers the manufacturing method for a battery in which positive electrode mix, electric conductive material and negative electrode gel are filled. (The best manner of practicing the invention) The present invention features coating of the petroleum wax type lubricant on the surface treating layer formed by metal plating on the steel plate or by heat treating in the air or in the non-oxidizing atmosphere after the metal plating. The petroleum wax type lubricant coated can remarkably improve the forming process such as the deep-drawing process. Furthermore, it eliminates its removal by degreasing and rinsing after the forming process, since most of the petroleum wax type lubricant adhered to the battery container can be volatilizingly removed by heating it at 200 to 350 °C. Due to the above, the surface treated steel sheet for the battery container having an excellent formability, which allows the cost to be reduced and the battery container, can be obtained. (Embodiment ) The present invention is explained in detail with examples as follows : First of all, the surface treating layer formed on the steel sheet of the present invention is explained. In general, the surface treated steel sheet for the battery container is required of excellent corrosion resistance in alkali solution, a contact resistance value which should be stable and low when the battery container is connected to the external terminal, and excellence in the spot welding when each component is welded and assembled at the time of battery manufacturing. The result of various examinations in these regards proved that the surface treating layer on the surface treated steel sheet for the battery container be a mono layer of either of the nickel plating layer, nickel-phosphorus alloy plating layer, nickel-iron alloy layer, nickel-tin alloy layer or the nickel-iron-tin alloy layer, or it be consisting of the multi-layers of the two or more of the above. In other words, the existence of the surface treating layer consisting of the nickel plating layer and/or the alloy layer based on nickel fully satisfies the aforementioned requirements. For the formation of this surface treating layer, either of the following methods can be applied after the degreasing, pickling and water rinsing of the steel sheet in a known method: (1) Method of electroplating (2) Method of electroless plating (3) Method of heat treating in the non-oxidizing atmosphere after elec troplating (4) Method of heat treating in the non-oxidizing atmosphere after electroless plating. For the method of forming the surface treating layer on the surface treated steel sheet for the battery container of the present invention, it is more desirable to use the method of (l) or (3) utilizing electroplating rather than to use the method of (2) or (4) utilizing electroless plating, in view of productivity. As the method of forming the surface treating layer by electroplating, the methods shown below is used. For example, the nickel plating layer is formed by electrolysis of the steel sheet as a cathode using known watt bath, sulfamic acid bath, borofluoride bath or chloride bath. The nickel-iron alloy layer is formed using a known method of the nickel-iron alloy plating bath including the nickel ion and the ferrous ion, however, nickel and iron are only eutectoid in this method, which requires heat treating in the non-oxidizing atmosphere for their alloying. Therefore, it is desirable in view of the plating conditions and the controlling of plating bath to practice the heat treatment after the nickel plating in the non-oxidizing atmosphere, followed by alloying all plated nickel. In case of forming the nickel-tin alloy layer, the nickel-tin alloy layer is formed using a known method of the nickel-tin alloy bath including the nickel ion and the stannous ion as in case of forming the nickel-iron alloy layer. In addition, either method of the following can be applied: a method of heat treating (reflow treatment) by resistance heating and/or induction heating in the air, which are known in manufacturing the tinplate, and a method of a heat treating in the non-oxidizing atmosphere. Prior to application of these methods, tin should be plated after the nickel plating, or nickel be plated after the tin plating, with a known nickel plating bath and tin bath. It is not desirable to plate nickel after the tin plating, followed by heat treating, since it is difficult to plate nickel evenly on the plated tin layer. It is therefore more desirable to plate tin after the nickel plating, followed by heat treating. Concerning formation of the nickel-tin-iron alloy layer, as well as the examples above, there is a known method of the alloy plating using the plating bath including all of each ion followed by heat treatment. However, as is the case of forming the nickel-tin alloy layer, it is more desirable, from the same viewpoint as the above, to plate tin after the nickel plating or the nickel-iron alloy plating, followed by heat treatment in the non-oxidizing atmosphere. When the heat treatment is practiced in the non-oxidizing atmosphere after nickel is plated on the steel sheet, the nickel-iron alloy layer is formed between the nickel plating layer and the steel sheet. There is a case where in the uppermost surface layer, only nickel exists or nickel and the nickel-iron alloy coexist, which can be selectively controlled depending on the nickel plating amount and the heat treating conditions. In the same manner, when heat treatment is practiced in the non-oxidizing atmosphere after the nickel plating on the steel sheet followed by the tin plating, the nickel-iron alloy layer, the nickel-tin alloy layer and the tin plating layer are formed in this order on the steel sheet. In another case, these surface treated layers coexist in the uppermost surface layer, which can be selectively controlled with ease depending on the nickel plating amount, the tin plating amount and the heat treating conditions. It is not desirable in terms of the battery performance that metal tin remains on the inside of the battery container. It is therefore required that the amount of tin plated on the side to be inside of the battery container after the forming process be limited in relation to the nickel plating amount, that is the amount of which all metal tin is alloyed by heat treatment. This matter is described later. Concerning the formation of the nickel-phosphorus alloy plating layer, a known method of the electroless plating bath is possibly applied, however, another known method of the nickel-phosphorus alloy plating bath (for example, Laid-open Japanese Patent No. Hei 2-129335) is desirable in terms of productivity. It was previously described that the uppermost surface of the surface treating layer on the surface treated steel sheet for the battery container of the present invention , be desirably the nickel plating layer or the layer of alloy based on nickel, in terms of the battery performance. Concerning the amount of the nickel plating, 5 to 45g/m2 is desirable, more desirably range of 15 to 35g/m2. In case where the amount of the nickel plating is less than 5g/m2, the plating can not cover fully on the surface of the steel sheet. In this container, the surface treated steel sheet which produces an excellent battery performance cannot be obtained. In case where amount of the nickel plating exceeds 45g/m2, the battery performance is saturated, which is not advantageous in terms of the cost. Next, concerning the formation of the nickel-tin alloy layer, it is required that all tin to be plated on the side to be the inside of the battery container in the forming process be alloyed into nickel-tin alloy. When part of the plated tin remains as metal tin after the alloying with nickel, the tin is dissolved into the potassium hydroxide solution, which is electrolyte of the alkali battery, and it generates hydrogen. This is undesirable as it will damage the battery performance remarkably. When heating is practiced at 700°C or less in the heat treating process, the nickel-tin alloy is mainly consisting of Ni 3 Sn, Ni3 s n 2 and Ni 3 Sn 4. Of these alloy composition, Ni 3Sn has the least ratio of tin to nickel (the atomic weight ratio of Ni : Sn is 3 : l). If, therefore, less amount of tin necessary to form Ni s Sn is plated, all tin will be alloyed with nickel. In other words, the tin plating amount should be 1/3 or less of that of the nickel plating amount in the atomic weight. In this respect, the atomic weight of tin is 118.6, and that of nickel is 58.7. Therefore, if the ratio of the tin plating amount is set at approx. 0.67 to the nickel plating amount as shown in the equation below, the atomic weight ratio of Ni : Sn will be 3 : 1. That is, the tin plating amount/the nickel plating amount=118.6/(58.7 x 3) =approx. 0.67. If the ratio of the tin plating amount exceeds 0.67 to the nickel plating amount, there may be metal tin remained even after heat treatment, which is not desirable for the battery performance as described above. Further more, even if no metal tin remains, the ratio of tin in the nickel-tin alloy layer will be great. An increase of the ratio of tin in the nickel-tin alloy layer may deteriorate the battery performance, therefore, it is undesirable. Accordingly, the ratio of the tin plating amount should be 0.67 or less to the nickel plating amount. A more desirable form of the surface treated steel sheet for the battery container of the present invention, is as follows: The surface treating layer formed on the side to be the inside of the battery container after the forming process be consisting of the nickel-iron alloy layer and the nickel-tin alloy layer, or the nickel-iron alloy layer and the nickel-tin-iron alloy layer, in such an order on the steel sheet. In any case, it is more desirable that the uppermost surface of the surface treating layer be consisting of the nickel-tin alloy layer or the nickel-tin-iron alloy layer rather than the plating layer of nickel alone. Such a nickel-tin alloy layer or nickel-tin-iron alloy layer shows a remarkably excellent battery performance. For example, the internal contact resistance of the battery is decreased remarkably. The reason for this cannot be explained clearly, however, it is supposed that on the surface of the nickel-tin alloy layer or the nickel-tin-iron alloy layer numerous cracks are formed with many asperities in the forming process, which increases the contact portion with the positive electrode mix. It reduces the contact resistance between the positive electrode mix and the inner surface of the battery container. Or, it is assumed that the values of the physical properties in the aforementioned alloys themselves (for example, low value of the electric resistance) may affect a decrease of the internal contact resistance of the battery. Concerning a more desirable construction of the surface treating layer mentioned above, the metal nickel layer as the intermediate layer may be formed between the nickel-iron alloy layer, formed on the steel sheet and the nickel-tin alloy layer or the nickel-tin-iron alloy layer as the over layer. This is desirable as it can improve the corrosion resistance without deteriorating the battery performance. Next, an example case where heat treatment is practiced in the non-oxidizing atmosphere after the metal plating as one step of the manufacturing method of the surface treated steel sheet for the battery container of the present invention will be explained. Heat treatment in the non-oxidizing atmosphere is desirable in terms of preventing oxidization of the uppermost surface of the surface treating layer. However, in container where the tin plating is practiced after nickel plating followed by alloying both of them by heat treatment, the resistance heating method and/or the induction heating method, which are generally used in the production of the tin-plate, are available for heating for a short period of time since nickel and tin are alloyed at 232 °C or more, which is the melting temperature of tin in the air. In case where the nickel-iron alloy layer is formed under the nickel-tin alloy layer to further improve the corrosion resistance, it is required that heat treatment be practiced at 450°C or more in the non-oxidizing atmosphere, since this nickel hardly diffuses into the steel sheet at such a temperature around the melting temperature of tin. Concretely, heating at 450 to 850 °C for 30 seconds to 15 hours is required. The box annealing method and the continuous annealing method are known as the method of heat treatment of the metal-plated steel sheet. Either method of these is available for the practice of the present invention. In the continuous annealing method, heat treatment at 600 to 850 °C for 30 seconds to 5 minutes is desirable while in the box annealing method, that at 450 to 650 °C for 5 to 15 hours is desirable. In case of forming the nickel-tin-iron alloy layer, it is required that heat-treatment be practiced at a comparatively high temperature for a long period of time so that three elemental components may diffuse into each other. In order to prevent the stretcher strain which occurs due to heat treatment, the temper rolling is required after the heat treatment. Since this temper rolling is the last finish rolling, the aimed surface roughness as well as the aimed surface appearance, such as the bright finish and the dull finish, can be obtained by changing the surface roughness of the work roll used in the temper rolling. Next, petroleum wax type lubricant to be coated on the above-mentioned surface finishing layer and coating method thereof, which is the characteristic of the surface finished steel sheet for the battery container of the present invention, will be explained. The petroleum wax type lubricant to be coated is selected from paraffin wax, micro crystalline wax, liquid paraffin, petrolatum, white petrolatum (Vaseline), polyethylene wax, polypropylene wax, and ethyl-ene propylene wax. The melting temperature of these lubricant is 35 to 80 °C and generally in the state of solid or gelatinous at normal temperature depending on the oxidized state. So they are easy to handle, since they get liquidity and easy to be coated by heating at the low temperature. Moreover, after being formed into the battery container, the coated petroleum wax type lubricant can be easily removed in the vaporization by heating at 200 to 350 °C for about 3 to 30 minutes in the air. Especially, white petrolatum (brand name: Sonojell-9, sold by Shima trade Inc.) of which melting temperature is about 42 °C can be removed only by heating for a short period of time at the low temperature. So it is more desirable. As for the amount of the petroleum wax type lubricant coated on the formed surface finishing layer, the range of 200 to 2000 mg/m2 is desirable, more desirably the range of 200 to 500 mg/m2. In case where the coating weight is less than 200 mg/m2, for instance, more than 10000 battery containers cannot be continuously deep-drawn at the speed of 50 containers/minute. Thus, the continuous production of them is obstructed. In addition, the side wall of the obtained battery container is occasionally scratched, and the metal die might be worn out more quickly, which is undesirable. Moreover, in case where the coating weight exceeds 2000 mg/m2, the amount of the above-mentioned lubricant that adheres to the surface of the obtained battery container is so large. So, it requires a long period of time to remove it in the vaporization by heating, though more than 10000 containers can be deep-drawn at a similar speed. It is undesirable. Moreover, in case where the majority of the petroleum wax type lubricant coated in rich amount remains inside and outside the battery container, the battery performance is deteriorated and the adhesion of coatings or printing ink that is coated on the outside the battery container is decreased. It is undesirable. Accordingly, it is desirable that the petroleum wax type lubricant should be coated as little as possible as far as the continuous production of battery container is not obstructed. The petroleum wax type lubricant is thermally melted by heating to the melting temperature (Tm) to Tm+100 °C and is coated on the above-mentioned surface treating layer. Coating is difficult in the temperature below the melting temperature, and the volatilization volume increases in the temperature that exceeds Tm+100°C, which is undesirable. Any coating method of the following can be applied: roll coating, spray coating and electrostatic coating. The battery container of the present invention is manufactured using known forming methods such as the deep-drawing process, DI process, and DS process. This battery container is manufactured from the surface treated steel sheet for battery container coated with the petroleum wax type lubricant as above-mentioned. The petroleum wax type lubricant coated on the surface treated steel sheet adheres inside and outside the obtained battery container. However, the part of it which adheres to the obtained battery container adheres to the metal die or the like during the forming process, and decreases somewhat from the original amount coated on the surface treated steel sheet. At any rate, since the petroleum wax type lubricant volatilizes at a high temperature, it can be easily removed by heating . The heating condition of the battery container depends on the kind and the coating weight of the coated petroleum wax type lubricant. The majority of the lubricant can be volatilizingly removed heating only for 1 to 30 minutes at a low temperature of 200 to 350 °C. The coated lubricant cannot be removed enough in vaporization even if the container is heated for a long period of time when it is heated at the temperature less than 200 °C, which obstructs the productivity of the battery container. The battery container can be heated at a high temperature of more than 350°C, but it is a loss of thermal energy and is economically undesirable. Both an electric oven and a gas oven can be used for the heating of the obtained battery container. The thus obtained surface treated steel sheet is coated with the above-mentioned petroleum wax type lubricant. Subsequently, this surface treated steel sheet is formed into a cylindrical, so-called two peace battery container having an integrated bottom portion and the wall portion, using one of following forming method : the deep drawing, the ironing after the deep drawing, and the stretch forming after the deep drawing. The forming method to be adopted is properly selected in consideration of the difficulty of the processing, the ca- i pacity of the battery, the strength of the container or the like. The formed battery container is heated for 3 to 30 minutes at the temperature of 200 to 350 °C, which removes the petroleum wax type lubricant that adheres on the surface of the battery. The petroleum wax type lubricant cannot be completely removed in vaporization at the temperature less than 200 °C, even if the battery container is heated for over 30 minutes. The higher the heating temperature, the more easily the petroleum wax type lubricant volatilizes, and the more the heating time shortens. However, in order to completely remove it by vaporization, the battery container should be heated for over three minutes. On the other hand, the steel sheet softens, and the strength of the battery container decreases when they are heated at the temperature more than 350 °C . For the above-mentioned reasons, the heating condition of the formed battery container is limited in the temperature of 200 to 350°C for 3 to 30 minutes. The thus obtained battery container is packed with the positive electrode mix, the electric conducting material, and the negative electrode gel, so that the battery is completed. Therefore, the present invention relates to a method to produce surface-coated steel sheet for a battery container comprising: degreasing and pickling a steel sheet in a known manner, forming a surface coated layer by plating or further heat treatment after plating on said steel sheet in a known manner, and subsequently coating a thermally melted petroleum wax type lubricant layer on the surface of said coated steel sheet heated to the melting temperature of said petroleum wax type lubricant (Tm) to Tm + 100°C. The present invention is explained concretely with examples and comparative examples, as follows. (Example) The low carbon aluminum killed steel sheet having thickness of 0.25 mm which was processed with cold rolling and annealing, was used as a substrate for metal plating. A chemical composition of the steel substrate is as follows: C:0.03% (% is the weight percent, it is the same for the following), Mn: 0.18 %, Si: 0.01 %, P: 0.013 %, S: 0.012 %, Al: 0.054 %, N: 0.0038 %. First, the above-mentioned steel sheet was electrolytically (cathodically) degreased in the alkali solution in the condition as follows: the density of caustic soda: 30 g/1, the bath temperature: 80 °C, the cathode current density: 10 A/dm2, the electrolysis duration: 20 seconds. After rinsing the steel sheet in clear water, it was pickled in the condition as follows: the density of sulfuric acid 50 g/1, the bath temperature 30°C, the dipping duration 5 seconds. Subsequently, after rinsing it in clean water, the metal plating was practiced in the various conditions shown in the following: (l) Nickel plating condition Bath composition: Nickel sulfate: 320 g/1. Nickel chloride: 40 g/1. Boric acid: 30 g/1. Semi-gloss agent on the market: (including unsat-urated alcohol polyoxyethylene and unsaturated carboxylic acid): 1.0 g/1. Sodium laurylate: 0.5 g/1. pH: 4.1~4.6. Bath temperature: 55 ± 2°C, Current density: 15 A/dm2. Anode: nickel pellet (The nickel pellets are filled in the titanium basket and the titanium basket is covered with a bag made of polypropylene). (2) Tin plating condition Bath composition: Stannous sulfate 30 g/1. Phenol sulfonic acid (65 % solution): 60 g/1. Ethoxylated a -naphthol: 5 g/1. Bath temperature: 50±2°C. Current density: 20 A/dm2. Anode: Tin plate. (3) Nickel-phosphorus alloy plating condition Bath composition: Nickel sulfate 150 g/1. Nickel chloride 80 g/1. Phosphorous acid 30 g/1. pH: 0.6. Bath temperature: 50 °C. Current density: 3 A/dm2. Anode: the same anode as used for the nickel plating. (Example 1 to 3) The nickel was plated on the steel sheet in the condition shown in above-mentioned (l). The amount of nickel plating was adjusted changing the electrolysis duration. The petroleum wax type lubricant shown in Table 1 was coated on the steel sheet after the nickel plating. (Example 4 to 6) The nickel plated steel sheet obtained in Example 1 to 3 was heat-treated in the condition of the soaking temperature of 550 °C and the soaking period of time of 6 hours in the non-oxidizing atmosphere having the dew point -40 °C and consisting of 6.5 % Hydrogen and nitrogen as for the rest. Subsequently, this steel sheet was temper rolled at the expansion rate of 1.0 %. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Example) The nickel of 20.0 g/m2 was plated on the steel sheet in the condition shown in above-mentioned (l). Then, the tin of 0.9g/m2 was plated on it in the condition shown in above-mentioned (2). Subsequently, the surface layer was alloyed into nickel-tin alloy in the air using the resistance heating method. After that, the petroleum wax type lubricant shown in Table 1 was coated on it. (Example 8 to 10) The steel sheet was nickel-plated in the condition shown in above-mentioned (l). Then, the surface treated steel sheet was tin-plated in the condition shown in above-mentioned (2). Next, this steel sheet was heat-treated in the condition of the soaking temperature of 700 °C and the soaking period of time of 3 minutes in the non-oxidizing atmosphere having the dew point -40 °C and consisting of 6.5% hydrogen and nitrogen as for the rest. Subsequently, the steel sheet was temper rolled at the expansion rate of 1.2%. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. The amount of nickel and that of tin were adjusted changing the electrolysis duration, respectively. (Example ll) The steel sheet was plated with nickel of 18.0g/m2 in the condition shown in above-mentioned (l). Subsequently, this sheet was plated with the nickel-phosphorus alloy of 5.8g/m2 (containing 12 % phosphorus) in the condition shown in above-mentioned (3). After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Example 12 to 14) The steel sheet was nickel plated in the condition shown in above-mentioned (l). Then, the surface treated steel sheet was plated with the nickel-phosphorus alloy (containing 10 to 12 % phosphorus) in the condition shown in above-mentioned (3). Next, this steel sheet was heat-treated in the condition of the soaking temperature of 650°C and the soaking period of time of 4 hours in the non-oxidizing atmosphere having the dew point -35 °C and consisting of 5.5% hydrogen and nitrogen as for the rest. Subsequently, this steel sheet was temper rolled at the expansion rate of 1.5%. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. The amount of nickel and that of phosphorus were adjusted changing the electrolysis duration, respectively. (Comparative Example l) The petroleum wax type lubricant shown on Table 1 was coated on the steel sheet plated with 4.0g/m2 of nickel in the condition above-mentioned (l). After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Comparative Example 2) The steel sheet was plated with 20.5 g/m2 of nickel in the condition above-mentioned (l). Subsequently, the heat-treatment and the temper rolling were practiced on the nickel plated steel sheet in the similar condition to those of Example 4 to 6. After that, the petroleum wax type lubricant shown on Table 1 was coated on this steel sheet. (Comparative Example 3) The steel sheet was plated with 8.0 g/m2 of nickel in the condition above-mentioned (l). Then, this sheet was plated with 1.2 g/m2 of tin. Subsequently, the heat-treatment was practiced on this nickel-tin plated steel sheet using the resistance heating method in the air. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Comparison Example 4) The steel sheet was plated with 35.0 g/m2 of nickel in the condition above-mentioned (l). Subsequently, this sheet was plated with 1.2 g/m2 of tin in the condition above-mentioned (2). After that, the heat-treatment and the temper rolling were practiced on this obtained surface treated steel sheet in a similar condition to those of Example 8 to 10. (Comparison Example 5) The steel sheet was plated with 36.0 g/m2 of nickel in the condition above-mentioned (l). Subsequently, this steel sheet was plated with nickel-phosphorus alloy ( nickel: 5.5 g/m2) in the condition above-mentioned (3). After that, the petroleum wax type lubricant shown in Table 1 was coated on the surface treated steel sheet. (Comparison Example 6) The heat treatment and the temper rolling were practiced on a similar surface treated steel sheet to that of Comparative Example 5 in a similar condition to those of Example 12 to 14. After that, the petroleum wax type lubricant shown in Table 1 was coated on this steel sheet. The ability of the continuous forming and the battery performance of the battery container were evaluated using the following method. The battery containers were manufactured from the surface treated steel sheet obtained in Example 1-14 and Comparative Example 1 to 6. The evaluation result was shown in Table 3 and Table 4 with the heating condition after forming. (l) Evaluation of the ability of continuous forming of the battery container The surface treated steel sheets for the battery container obtained in Example 1 to 14 and Comparison Example 1 to 6 was punched out into the blank. Then, the blank was continuously formed into a cylindrical container having 49.3 mm in the height and 13.8 mm in outside diameter using a drawing process (drawing speed: 50 containers/minute) consisting of eight steps. After that, the upper edge portion was trimmed, and thus the battery container was completed. The ability of continuous forming was evaluated by the standard shown as follows: ©: It was possible to continuously form more than 10000 containers without any scratches on the side wall of the container. O: It was possible to continuously form 5000-10000 containers without any scratches on the side wall of the container, but impossible to continuously form more than 10000 of them without causing scratches. A: It was possible to continuously form 2000 to 5000 containers with- out any scratches on the side wall of the container, but impossible to continuously form more than 5000 of them without causing scratches. X : Many scratches frequently occurred on the side wall of the container, and less than 2000 containers could be continuously formed. (2) Evaluation of battery performance The battery container that had been obtained by the method above-mentioned 1 was heat-treated in the condition in Table 3 and Table 4. The alkali manganese battery was manufactured from this battery container by the following method. First, the manganese dioxide and the graphite were gathered at a rate of 10:1 by the weight ratio. Subsequently, the potassium hydroxide (8 moles) was mixed with this . Thus, the positive electrode mix was prepared. Then, the positive electrode mix was shaped into a fixed size doughnut type pellet by pressing in the metal mold. Next, this pellet was inserted and fixed in the obtained battery container with pressure. Next, in order to install the negative electrode plate that was spot-welded with the negative electrode collector rod in the battery container, the fixed position under opening edge of the battery container was processed in the neck-in. Next, the separator comprising the un-woven cloth made of the vinylon was inserted along the internal circumference of the pellet that was pressed into the battery container. Then, the negative electrode gel comprising the potassium hydroxide saturated with zinc granules and zinc oxide was inserted in the battery container. After, that, the negative electrode plate installed with the gasket of the insulating material was inserted in the battery container followed by calking. Thus, the alkali manganese battery was completed. After this alkali manganese battery was left in the room temperature for 24 hours, the battery performance was measured. The battery performance was evaluated by two items which were the internal resistance values (m Q) by the alternating current impedance (frequency 1kHz) and short-circuit current values (A) at 1m Q. charge. Both of the internal resistance value and the short-circuit current value were measured at the temperature of 20 °C. The evaluation results of the ability of the continuous forming of the battery container and the battery performance of them are shown in Table 3 and Table 4 with the heating condition of the battery container. The kind of petroleum wax type lubricant coated on the surface treated steel sheet is displayed in Table 1 and Table 2 using the following signs. A: Paraffin wax B: Micro crystalline wax C: Liquid paraffin D: Petrolatum E: White petrolatum (Vaseline). The overall evaluation in Table 3 and Table 4 is shown as follows: The one that is marked with © is excellent in the continuous forming of the battery container, and its internal resistance value is low, and its short-circuit current value is great. The one that is marked with O excellent in the continuous forming of the battery container, and is a little inferior in the battery performances but no problem on practi- cal use. The one that is marked with X is inferior in either of the continuous forming of the battery container or the battery performance. The evaluation result in Table 3 and 4 is concluded as follows: (1) Of the surface treated steel sheets for the battery container of the present invention, that having the uppermost layer of nickel tin alloy (Example 7 to 10) is more excellent in the battery performance than that having a nickel based layer (Example 1 to 6) or that having nickel-phosphorus alloy layer (Example 11 to 14). (2) The reason why the battery performance of the nickel plated steel sheet of Comparative Example 1 is inferior to the surface treated steel sheet of Example 1 to 6 is that the amount of plated nickel is less. The reason why the continuous forming ability of the battery container by the surface treated steel sheet having a nickel based layer of Compara tive Example 2 is inferior is that the coated petroleum wax type lubri cant is less. (3) The battery performance inferiority of the surface treated steel sheet having nickel-tin alloy layer of Comparative Example 3 is due to the metallic tin remaining on the surface, and a large amount of the pe troleum wax type lubricant remaining on the obtained battery container since the said lubricant was coated too much. The reason why the bat tery performance of the surface treated steel sheet having nickel-tin alloy layer of Comparative Example 4 is inferior is that the said lu bricant remained although it was coated in a small amount since the heating temperature of the obtained battery container was low. (4) The surface treated steel sheet having nickel-phosphorus alloy layer of Comparative Example 5 is inferior in the ability of continuous forming into the battery container, because the said lubricant was coated too little. Moreover, the heating duration of the obtained battery container was short, and the said lubricant remained, so that the battery performance is also inferior. (5) As for the surface treated steel sheet having nickel-phosphorus alloy layer shown in Comparative Example 6, it is excellent in the ability of continuous forming into the battery container. Its battery performance is as good as those of Example 11 to 14. But, it was a case where the obtained battery container was heated for a long period of time. Such a case is undesirable in the viewpoint of the productivity of battery container and the cost reduction. For these examples and comparative examples, it is understood that the surface treated steel sheet for the battery container described in the claims of the present invention is more excellent in the continuous forming of the battery container. In addition, it is understood that the battery, that is manufactured from the battery container using said surface treated steel sheet after heating on the specified condition, has excellent battery performance. ( Table 1) State of obtained surface treated steel sheet (Table Removed) ( Table 2 ) State of obtained surface treated steel sheet (Table Removed) ( Table 3 ) The heating condition after formed into the battery container, and the evaluation result of the performance (Table Removed) ( Table 4 ) The heating condition after formed into the battery container, and the characteristic evaluation result of the performance (Table Removed) ( Effect of the invention ) It is possible to form the surface treated steel sheet for the battery container of the present invention more efficiently than the conventional one, wherein the blank and the metal mold must be coated with the lubricant in every container just before forming it into the battery container. It is also unnecessary degreasing the coated lubricant, rinsing and drying after forming into the battery container, which were essential in the past. The heat treatment just at the low temperature of 200 to 350°C can easily remove the majority of lubricants. This manufacturing method can efficiently produce batteries having excellent battery performance with reduced cost, so the industrial value is extremely high. Summary ( objective ) A surface treated steel sheet for a battery container having excellent formability and battery performance and manufacturing method thereof are offered and the battery container using the said surface treated steel sheet is manufactured efficiently and at a low-cost. ( Solution ) First, the surface treated steel sheet, which is manufactured by plating after degreasing and pickling, or further heating after plating, is heated to the melting temperature of the petroleum wax type lubricant to be coated (Tm) to Tm+100°C. Next, the melted above-mentioned lubricant is coated to the surface. Then, this surface treated steel sheet is formed into the battery container by the deep drawing, the DI processing or the DS processing. After that, the steel sheet is heat-treated at the low temperature of 200 to 350°C. WE CLAIM: 1. A method to produce surface-coated steel sheet for a battery container comprising: degreasing and pickling a steel sheet in a known manner, forming a surface coated layer by plating or further heat treatment after plating on said steel sheet in a known manner, and subsequently coating a thermally melted petroleum wax type lubricant layer on the surface of said coated steel sheet heated to the melting temperature of said petroleum wax type lubricant (Tm) to Tm + 100°C. 2. The method as claimed in claim 1, wherein said surface-coated layer consists of either nickel plating layer or nickel-phosphorus alloy plating layer, or two layers comprising both layers. 3. The method as claimed in claim 1, wherein said surface coated layer is formed by plating nickel or nickel phosphorous alloy and tin on it, and said heat treatment is in the air or in an non-oxidizing atmosphere. 6. A method to produce surface-coated steel sheet for a battery container substantially as herein described with reference to and as illustrated in the foregoing examples.

Full Text

Specification
(Field of the invention)
The present invention relates to the surface-treated steel sheet for a battery container, production method thereof, a battery container utilizing said surf ace-treated steel sheet and manufacturing method thereof, and a battery utilizing said battery container.
In more details, the invention relates to the surface-treated steel sheet suitable for a battery container and production method thereof, and a battery container manufactured from said surface-treated steel sheet and manufacturing method thereof, a battery using said surface-treated steel sheet, in which a cylindrical container having an integrated bottom portion and wall portion formed by a severe forming process such as deep drawing, drawing and ironing (hereinafter called DI process), or drawing and stretch forming (hereinafter called DS process). (Prior Art)
It has become a main stream in recent years to manufacture a battery container using deep drawing the surface-treated steel sheet after being nickel plated or heat treated after plating as a battery container manufacturing method in which strong alkali solution is packed for use in alkali-manganese battery or nickel cadmium battery,
instead of the conventional barrel plating method after deep drawing a steel sheet into a battery container.
Especially, the DI process has recently been used for the manufacture of battery containers in view of increasing battery capacity, material cost reduction by reducing the wall thickness and also the further improvement of battery capacity. In view of similar points as mentioned above, the manufacturing method using the DS process has also been studied. The spread of these battery container manufacturing methods has resulted in the increasing demand for battery container materials having not only excellent battery performance but also excellent formability.
Generally, in the battery container manufacturing, it has been a common practice to coat a lubricant on battery container material such as nickel plated steel sheets prior to the forming process such as additional drawing, and then the lubricant is removed by degreasing and rinsing after the forming process, and then dried. (Objective of the present invention)
The conventional battery container manufacturing methods as explained above require such extremely troublesome operations to uniformly coat a lubricant on battery container materials just prior to press forming, or to drip a lubricant while press forming. Moreover, it is inevitably required to carry out two additional processes after the forming process for a battery container; namely, removal of lubricant by degreasing-rinsing and drying after rinsing.
As explained above, the conventional battery container manufac-
turing methods have been extremely unsatisfactory in view of elimination of labor, water resources and thermal energy consumption.
The present invention will allow to solve all these problems at the same time, and the objective is to provide a surface-treated steel sheet for a battery container which is excellent in battery performance and formability and production method thereof, battery container made of said surface-treated steel sheet and manufacturing method thereof, and a battery using said battery container. (Means to solve the problem)
The present invention for the surface-treated steel sheet for a battery container is characterized in that a petroleum wax type lubricant is coated on the surface- treated layer, after the steel sheet is degreased and pickled, and then plated, or further heat treated after plated.
It is preferable that the surface-treated layer should have mono layer or a multiple layer consisting one layer or more than two layers including any one of nickel layer, nickel-phosphorus alloy layer, nickel-iron alloy layer, nickel-tin alloy layer, nickel-phosphorus-tin layer, or nickel-tin-iron alloy layer, and it is also preferable that the surf ace-treated layer should contain 1 to 45kg/m2 of nickel.
It is also characterized in that the surface-treated layer is a mono layer or a multiple layer consisting of one or more than two types of layers including nickel-tin-alloy layer, nickel-phosphorus-tin alloy layer, or nickel-tin-iron alloy layer, with the tin content in
the ratio of not more than 0.67 (by weight-ratio to the plating weight of nickel).
Furthermore, it is characterized in that said petroleum wax type lubricant consists of any one of paraffin wax, micro crystalline wax, fluid paraffin, petrolatum, white petrolatum, polyethylene wax, polypropylene wax, ethylene-propylene wax, and it is also characterized in that the coating weight of said petroleum wax type lubricant should be 200 to 2000 mg/m2.
The present invention is also characterized by the production method for the surface-treated steel sheet which is plated after de-greasing and pickling, or heat treated after plating to form a surface-treated layer, and then heated to the melting temperature of the petroleum wax type lubricant (Tm) to Tm +100 ° C and coated with a thermally molten petroleum wax type lubricant on its surface.
It is characterized in that the steel sheet is plated with nickel or nickel-phosphorus alloy after degreasing and pickling the steel sheet, or it is further heat treated in a non-oxidizing atmosphere after nickel plating or nickel-phosphorus alloy plating, and it is also characterized in that the steel sheet is plated with nickel or nickel-phosphorus alloy, and then it is further plated with tin on it, and then heat-treated in the air or non-oxidizing atmosphere.
And it is characterized that the surface-treated steel sheet is coated with 200 to 2000 mg/m 2 of said petroleum wax type lubricant.
In addition, the manufacturing method for a battery container of the present invention is characterized in that this cylindrical bat-
tery container having an integrated bottom portion and wall portion is heat-treated at 200 to 350°C for 3 to 30 minutes, after the surface-treated steel sheet is formed into a cylindrical battery container having an integrated bottom portion and wall portion by deep drawing, ironing after deep drawing, stretch forming after deep drawing, and the present invention also covers the manufacturing method for a battery in which positive electrode mix, electric conductive material and negative electrode gel are filled. (The best manner of practicing the invention)
The present invention features coating of the petroleum wax type lubricant on the surface treating layer formed by metal plating on the steel plate or by heat treating in the air or in the non-oxidizing atmosphere after the metal plating.
The petroleum wax type lubricant coated can remarkably improve the forming process such as the deep-drawing process. Furthermore, it eliminates its removal by degreasing and rinsing after the forming process, since most of the petroleum wax type lubricant adhered to the battery container can be volatilizingly removed by heating it at 200 to 350 °C. Due to the above, the surface treated steel sheet for the battery container having an excellent formability, which allows the cost to be reduced and the battery container, can be obtained. (Embodiment )
The present invention is explained in detail with examples as follows : First of all, the surface treating layer formed on the steel sheet of the present invention is explained.
In general, the surface treated steel sheet for the battery container is required of excellent corrosion resistance in alkali solution, a contact resistance value which should be stable and low when the battery container is connected to the external terminal, and excellence in the spot welding when each component is welded and assembled at the time of battery manufacturing.
The result of various examinations in these regards proved that the surface treating layer on the surface treated steel sheet for the battery container be a mono layer of either of the nickel plating layer, nickel-phosphorus alloy plating layer, nickel-iron alloy layer, nickel-tin alloy layer or the nickel-iron-tin alloy layer, or it be consisting of the multi-layers of the two or more of the above. In other words, the existence of the surface treating layer consisting of the nickel plating layer and/or the alloy layer based on nickel fully satisfies the aforementioned requirements.
For the formation of this surface treating layer, either of the following methods can be applied after the degreasing, pickling and water rinsing of the steel sheet in a known method:
(1) Method of electroplating
(2) Method of electroless plating
(3) Method of heat treating in the non-oxidizing atmosphere after elec
troplating
(4) Method of heat treating in the non-oxidizing atmosphere after
electroless plating.
For the method of forming the surface treating layer on the surface
treated steel sheet for the battery container of the present invention, it is more desirable to use the method of (l) or (3) utilizing electroplating rather than to use the method of (2) or (4) utilizing electroless plating, in view of productivity.
As the method of forming the surface treating layer by electroplating, the methods shown below is used. For example, the nickel plating layer is formed by electrolysis of the steel sheet as a cathode using known watt bath, sulfamic acid bath, borofluoride bath or chloride bath.
The nickel-iron alloy layer is formed using a known method of the nickel-iron alloy plating bath including the nickel ion and the ferrous ion, however, nickel and iron are only eutectoid in this method, which requires heat treating in the non-oxidizing atmosphere for their alloying. Therefore, it is desirable in view of the plating conditions and the controlling of plating bath to practice the heat treatment after the nickel plating in the non-oxidizing atmosphere, followed by alloying all plated nickel.
In case of forming the nickel-tin alloy layer, the nickel-tin alloy layer is formed using a known method of the nickel-tin alloy bath including the nickel ion and the stannous ion as in case of forming the nickel-iron alloy layer. In addition, either method of the following can be applied: a method of heat treating (reflow treatment) by resistance heating and/or induction heating in the air, which are known in manufacturing the tinplate, and a method of a heat treating in the non-oxidizing atmosphere. Prior to application of these methods, tin
should be plated after the nickel plating, or nickel be plated after the tin plating, with a known nickel plating bath and tin bath. It is not desirable to plate nickel after the tin plating, followed by heat treating, since it is difficult to plate nickel evenly on the plated tin layer.
It is therefore more desirable to plate tin after the nickel plating, followed by heat treating.
Concerning formation of the nickel-tin-iron alloy layer, as well as the examples above, there is a known method of the alloy plating using the plating bath including all of each ion followed by heat treatment. However, as is the case of forming the nickel-tin alloy layer, it is more desirable, from the same viewpoint as the above, to plate tin after the nickel plating or the nickel-iron alloy plating, followed by heat treatment in the non-oxidizing atmosphere.
When the heat treatment is practiced in the non-oxidizing atmosphere after nickel is plated on the steel sheet, the nickel-iron alloy layer is formed between the nickel plating layer and the steel sheet.
There is a case where in the uppermost surface layer, only nickel exists or nickel and the nickel-iron alloy coexist, which can be selectively controlled depending on the nickel plating amount and the heat treating conditions.
In the same manner, when heat treatment is practiced in the non-oxidizing atmosphere after the nickel plating on the steel sheet followed by the tin plating, the nickel-iron alloy layer, the nickel-tin alloy layer and the tin plating layer are formed in this
order on the steel sheet. In another case, these surface treated layers coexist in the uppermost surface layer, which can be selectively controlled with ease depending on the nickel plating amount, the tin plating amount and the heat treating conditions. It is not desirable in terms of the battery performance that metal tin remains on the inside of the battery container. It is therefore required that the amount of tin plated on the side to be inside of the battery container after the forming process be limited in relation to the nickel plating amount, that is the amount of which all metal tin is alloyed by heat treatment.
This matter is described later. Concerning the formation of the nickel-phosphorus alloy plating layer, a known method of the electroless plating bath is possibly applied, however, another known method of the nickel-phosphorus alloy plating bath (for example, Laid-open Japanese Patent No. Hei 2-129335) is desirable in terms of productivity.
It was previously described that the uppermost surface of the surface treating layer on the surface treated steel sheet for the battery container of the present invention , be desirably the nickel plating layer or the layer of alloy based on nickel, in terms of the battery performance. Concerning the amount of the nickel plating, 5 to 45g/m2 is desirable, more desirably range of 15 to 35g/m2. In case where the amount of the nickel plating is less than 5g/m2, the plating can not cover fully on the surface of the steel sheet. In this container, the surface treated steel sheet which produces an excellent battery performance cannot be obtained.
In case where amount of the nickel plating exceeds 45g/m2, the battery performance is saturated, which is not advantageous in terms of the cost.
Next, concerning the formation of the nickel-tin alloy layer, it is required that all tin to be plated on the side to be the inside of the battery container in the forming process be alloyed into nickel-tin alloy.
When part of the plated tin remains as metal tin after the alloying with nickel, the tin is dissolved into the potassium hydroxide solution, which is electrolyte of the alkali battery, and it generates hydrogen. This is undesirable as it will damage the battery performance remarkably. When heating is practiced at 700°C or less in the heat treating process, the nickel-tin alloy is mainly consisting of Ni 3 Sn, Ni3 s n 2 and Ni 3 Sn 4.
Of these alloy composition, Ni 3Sn has the least ratio of tin to nickel (the atomic weight ratio of Ni : Sn is 3 : l). If, therefore, less amount of tin necessary to form Ni s Sn is plated, all tin will be alloyed with nickel.
In other words, the tin plating amount should be 1/3 or less of that of the nickel plating amount in the atomic weight.
In this respect, the atomic weight of tin is 118.6, and that of nickel is 58.7. Therefore, if the ratio of the tin plating amount is set at approx. 0.67 to the nickel plating amount as shown in the equation below, the atomic weight ratio of Ni : Sn will be 3 : 1. That is, the tin plating amount/the nickel plating amount=118.6/(58.7 x 3)
=approx. 0.67.
If the ratio of the tin plating amount exceeds 0.67 to the nickel plating amount, there may be metal tin remained even after heat treatment, which is not desirable for the battery performance as described above.
Further more, even if no metal tin remains, the ratio of tin in the nickel-tin alloy layer will be great.
An increase of the ratio of tin in the nickel-tin alloy layer may deteriorate the battery performance, therefore, it is undesirable.
Accordingly, the ratio of the tin plating amount should be 0.67 or less to the nickel plating amount.
A more desirable form of the surface treated steel sheet for the battery container of the present invention, is as follows: The surface treating layer formed on the side to be the inside of the battery container after the forming process be consisting of the nickel-iron alloy layer and the nickel-tin alloy layer, or the nickel-iron alloy layer and the nickel-tin-iron alloy layer, in such an order on the steel sheet. In any case, it is more desirable that the uppermost surface of the surface treating layer be consisting of the nickel-tin alloy layer or the nickel-tin-iron alloy layer rather than the plating layer of nickel alone.
Such a nickel-tin alloy layer or nickel-tin-iron alloy layer shows a remarkably excellent battery performance.
For example, the internal contact resistance of the battery is decreased remarkably.
The reason for this cannot be explained clearly, however, it is supposed that on the surface of the nickel-tin alloy layer or the nickel-tin-iron alloy layer numerous cracks are formed with many asperities in the forming process, which increases the contact portion with the positive electrode mix. It reduces the contact resistance between the positive electrode mix and the inner surface of the battery container.
Or, it is assumed that the values of the physical properties in the aforementioned alloys themselves (for example, low value of the electric resistance) may affect a decrease of the internal contact resistance of the battery.
Concerning a more desirable construction of the surface treating layer mentioned above, the metal nickel layer as the intermediate layer may be formed between the nickel-iron alloy layer, formed on the steel sheet and the nickel-tin alloy layer or the nickel-tin-iron alloy layer as the over layer. This is desirable as it can improve the corrosion resistance without deteriorating the battery performance.
Next, an example case where heat treatment is practiced in the non-oxidizing atmosphere after the metal plating as one step of the manufacturing method of the surface treated steel sheet for the battery container of the present invention will be explained.
Heat treatment in the non-oxidizing atmosphere is desirable in terms of preventing oxidization of the uppermost surface of the surface treating layer. However, in container where the tin plating is practiced after nickel plating followed by alloying both of them by
heat treatment, the resistance heating method and/or the induction heating method, which are generally used in the production of the tin-plate, are available for heating for a short period of time since nickel and tin are alloyed at 232 °C or more, which is the melting temperature of tin in the air.
In case where the nickel-iron alloy layer is formed under the nickel-tin alloy layer to further improve the corrosion resistance, it is required that heat treatment be practiced at 450°C or more in the non-oxidizing atmosphere, since this nickel hardly diffuses into the steel sheet at such a temperature around the melting temperature of tin.
Concretely, heating at 450 to 850 °C for 30 seconds to 15 hours is required. The box annealing method and the continuous annealing method are known as the method of heat treatment of the metal-plated steel sheet. Either method of these is available for the practice of the present invention. In the continuous annealing method, heat treatment at 600 to 850 °C for 30 seconds to 5 minutes is desirable while in the box annealing method, that at 450 to 650 °C for 5 to 15 hours is desirable.
In case of forming the nickel-tin-iron alloy layer, it is required that heat-treatment be practiced at a comparatively high temperature for a long period of time so that three elemental components may diffuse into each other.
In order to prevent the stretcher strain which occurs due to heat treatment, the temper rolling is required after the heat treatment. Since this temper rolling is the last finish rolling, the aimed surface roughness as well as the aimed surface appearance, such as the bright
finish and the dull finish, can be obtained by changing the surface roughness of the work roll used in the temper rolling.
Next, petroleum wax type lubricant to be coated on the above-mentioned surface finishing layer and coating method thereof, which is the characteristic of the surface finished steel sheet for the battery container of the present invention, will be explained.
The petroleum wax type lubricant to be coated is selected from paraffin wax, micro crystalline wax, liquid paraffin, petrolatum, white petrolatum (Vaseline), polyethylene wax, polypropylene wax, and ethyl-ene propylene wax. The melting temperature of these lubricant is 35 to 80 °C and generally in the state of solid or gelatinous at normal temperature depending on the oxidized state. So they are easy to handle, since they get liquidity and easy to be coated by heating at the low temperature.
Moreover, after being formed into the battery container, the coated petroleum wax type lubricant can be easily removed in the vaporization by heating at 200 to 350 °C for about 3 to 30 minutes in the air. Especially, white petrolatum (brand name: Sonojell-9, sold by Shima trade Inc.) of which melting temperature is about 42 °C can be removed only by heating for a short period of time at the low temperature. So it is more desirable.
As for the amount of the petroleum wax type lubricant coated on the formed surface finishing layer, the range of 200 to 2000 mg/m2 is desirable, more desirably the range of 200 to 500 mg/m2. In case where the coating weight is less than 200 mg/m2, for instance, more than
10000 battery containers cannot be continuously deep-drawn at the speed of 50 containers/minute. Thus, the continuous production of them is obstructed. In addition, the side wall of the obtained battery container is occasionally scratched, and the metal die might be worn out more quickly, which is undesirable. Moreover, in case where the coating weight exceeds 2000 mg/m2, the amount of the above-mentioned lubricant that adheres to the surface of the obtained battery container is so large. So, it requires a long period of time to remove it in the vaporization by heating, though more than 10000 containers can be deep-drawn at a similar speed. It is undesirable.
Moreover, in case where the majority of the petroleum wax type lubricant coated in rich amount remains inside and outside the battery container, the battery performance is deteriorated and the adhesion of coatings or printing ink that is coated on the outside the battery container is decreased. It is undesirable. Accordingly, it is desirable that the petroleum wax type lubricant should be coated as little as possible as far as the continuous production of battery container is not obstructed. The petroleum wax type lubricant is thermally melted by heating to the melting temperature (Tm) to Tm+100 °C and is coated on the above-mentioned surface treating layer. Coating is difficult in the temperature below the melting temperature, and the volatilization volume increases in the temperature that exceeds Tm+100°C, which is undesirable. Any coating method of the following can be applied: roll coating, spray coating and electrostatic coating.
The battery container of the present invention is manufactured
using known forming methods such as the deep-drawing process, DI process, and DS process. This battery container is manufactured from the surface treated steel sheet for battery container coated with the petroleum wax type lubricant as above-mentioned.
The petroleum wax type lubricant coated on the surface treated steel sheet adheres inside and outside the obtained battery container. However, the part of it which adheres to the obtained battery container adheres to the metal die or the like during the forming process, and decreases somewhat from the original amount coated on the surface treated steel sheet. At any rate, since the petroleum wax type lubricant volatilizes at a high temperature, it can be easily removed by heating . The heating condition of the battery container depends on the kind and the coating weight of the coated petroleum wax type lubricant. The majority of the lubricant can be volatilizingly removed heating only for 1 to 30 minutes at a low temperature of 200 to 350 °C. The coated lubricant cannot be removed enough in vaporization even if the container is heated for a long period of time when it is heated at the temperature less than 200 °C, which obstructs the productivity of the battery container. The battery container can be heated at a high temperature of more than 350°C, but it is a loss of thermal energy and is economically undesirable. Both an electric oven and a gas oven can be used for the heating of the obtained battery container.
The thus obtained surface treated steel sheet is coated with the above-mentioned petroleum wax type lubricant. Subsequently, this surface treated steel sheet is formed into a cylindrical, so-called
two peace battery container having an integrated bottom portion and the wall portion, using one of following forming method : the deep drawing, the ironing after the deep drawing, and the stretch forming after the deep drawing. The forming method to be adopted is properly selected in consideration of the difficulty of the processing, the ca-
i
pacity of the battery, the strength of the container or the like. The formed battery container is heated for 3 to 30 minutes at the temperature of 200 to 350 °C, which removes the petroleum wax type lubricant that adheres on the surface of the battery. The petroleum wax type lubricant cannot be completely removed in vaporization at the temperature less than 200 °C, even if the battery container is heated for over 30 minutes. The higher the heating temperature, the more easily the petroleum wax type lubricant volatilizes, and the more the heating time shortens. However, in order to completely remove it by vaporization, the battery container should be heated for over three minutes. On the other hand, the steel sheet softens, and the strength of the battery container decreases when they are heated at the temperature more than 350 °C . For the above-mentioned reasons, the heating condition of the formed battery container is limited in the temperature of 200 to 350°C for 3 to 30 minutes. The thus obtained battery container is packed with the positive electrode mix, the electric conducting material, and the negative electrode gel, so that the battery is completed.
Therefore, the present invention relates to a method to produce surface-coated steel sheet for a battery container comprising:
degreasing and pickling a steel sheet in a known manner, forming a surface coated layer by plating or further heat treatment after plating on said steel sheet in a known manner, and subsequently coating a thermally melted petroleum wax type lubricant layer on the surface of said coated steel sheet heated to the melting temperature of said petroleum wax type lubricant (Tm) to Tm + 100°C.
The present invention is explained concretely with examples and comparative examples, as follows.
(Example)
The low carbon aluminum killed steel sheet having thickness of 0.25 mm which was processed with cold rolling and annealing, was used as a substrate for metal plating. A chemical composition of the steel substrate is as follows:
C:0.03% (% is the weight percent, it is the same for the following), Mn: 0.18 %, Si: 0.01 %, P: 0.013 %, S: 0.012 %, Al: 0.054 %, N: 0.0038 %.
First, the above-mentioned steel sheet was electrolytically (cathodically) degreased in the alkali solution in the condition as follows: the density of caustic soda: 30 g/1, the bath temperature: 80 °C, the cathode current density: 10 A/dm2, the electrolysis duration: 20 seconds.
After rinsing the steel sheet in clear water, it was pickled in the condition as follows: the density of sulfuric acid 50 g/1, the bath temperature 30°C, the dipping duration 5 seconds. Subsequently, after rinsing it in clean water, the metal plating was practiced in the various conditions shown in the following: (l) Nickel plating condition
Bath composition: Nickel sulfate: 320 g/1. Nickel chloride: 40 g/1. Boric acid: 30 g/1. Semi-gloss agent on the market: (including unsat-urated alcohol polyoxyethylene and unsaturated carboxylic acid): 1.0 g/1. Sodium laurylate: 0.5 g/1. pH: 4.1~4.6. Bath temperature: 55 ± 2°C, Current density: 15 A/dm2. Anode: nickel pellet (The nickel pellets are filled in the titanium basket and the titanium basket is
covered with a bag made of polypropylene).
(2) Tin plating condition
Bath composition: Stannous sulfate 30 g/1. Phenol sulfonic acid (65 % solution): 60 g/1. Ethoxylated a -naphthol: 5 g/1. Bath temperature: 50±2°C. Current density: 20 A/dm2. Anode: Tin plate.
(3) Nickel-phosphorus alloy plating condition
Bath composition: Nickel sulfate 150 g/1. Nickel chloride 80 g/1. Phosphorous acid 30 g/1. pH: 0.6. Bath temperature: 50 °C.
Current density: 3 A/dm2. Anode: the same anode as used for the nickel plating. (Example 1 to 3)
The nickel was plated on the steel sheet in the condition shown in above-mentioned (l). The amount of nickel plating was adjusted changing the electrolysis duration. The petroleum wax type lubricant shown in Table 1 was coated on the steel sheet after the nickel plating. (Example 4 to 6)
The nickel plated steel sheet obtained in Example 1 to 3 was heat-treated in the condition of the soaking temperature of 550 °C and the soaking period of time of 6 hours in the non-oxidizing atmosphere having the dew point -40 °C and consisting of 6.5 % Hydrogen and nitrogen as for the rest. Subsequently, this steel sheet was temper rolled at the expansion rate of 1.0 %. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Example)

The nickel of 20.0 g/m2 was plated on the steel sheet in the condition shown in above-mentioned (l). Then, the tin of 0.9g/m2 was plated on it in the condition shown in above-mentioned (2). Subsequently, the surface layer was alloyed into nickel-tin alloy in the air using the resistance heating method.
After that, the petroleum wax type lubricant shown in Table 1 was coated on it. (Example 8 to 10)
The steel sheet was nickel-plated in the condition shown in above-mentioned (l). Then, the surface treated steel sheet was tin-plated in the condition shown in above-mentioned (2). Next, this steel sheet was heat-treated in the condition of the soaking temperature of 700 °C and the soaking period of time of 3 minutes in the non-oxidizing atmosphere having the dew point -40 °C and consisting of 6.5% hydrogen and nitrogen as for the rest. Subsequently, the steel sheet was temper rolled at the expansion rate of 1.2%. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. The amount of nickel and that of tin were adjusted changing the electrolysis duration, respectively. (Example ll)
The steel sheet was plated with nickel of 18.0g/m2 in the condition shown in above-mentioned (l). Subsequently, this sheet was plated with the nickel-phosphorus alloy of 5.8g/m2 (containing 12 % phosphorus) in the condition shown in above-mentioned (3). After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained

surface treated steel sheet. (Example 12 to 14)
The steel sheet was nickel plated in the condition shown in above-mentioned (l). Then, the surface treated steel sheet was plated with the nickel-phosphorus alloy (containing 10 to 12 % phosphorus) in the condition shown in above-mentioned (3). Next, this steel sheet was heat-treated in the condition of the soaking temperature of 650°C and the soaking period of time of 4 hours in the non-oxidizing atmosphere having the dew point -35 °C and consisting of 5.5% hydrogen and nitrogen as for the rest. Subsequently, this steel sheet was temper rolled at the expansion rate of 1.5%. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. The amount of nickel and that of phosphorus were adjusted changing the electrolysis duration, respectively. (Comparative Example l)
The petroleum wax type lubricant shown on Table 1 was coated on the steel sheet plated with 4.0g/m2 of nickel in the condition above-mentioned (l). After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Comparative Example 2)
The steel sheet was plated with 20.5 g/m2 of nickel in the condition above-mentioned (l). Subsequently, the heat-treatment and the temper rolling were practiced on the nickel plated steel sheet in the similar condition to those of Example 4 to 6. After that, the petroleum wax type lubricant shown on Table 1 was coated on this steel sheet.
(Comparative Example 3)
The steel sheet was plated with 8.0 g/m2 of nickel in the condition above-mentioned (l). Then, this sheet was plated with 1.2 g/m2 of tin. Subsequently, the heat-treatment was practiced on this nickel-tin plated steel sheet using the resistance heating method in the air. After that, the petroleum wax type lubricant shown in Table 1 was coated on the obtained surface treated steel sheet. (Comparison Example 4)
The steel sheet was plated with 35.0 g/m2 of nickel in the condition above-mentioned (l). Subsequently, this sheet was plated with 1.2 g/m2 of tin in the condition above-mentioned (2). After that, the heat-treatment and the temper rolling were practiced on this obtained surface treated steel sheet in a similar condition to those of Example 8 to 10. (Comparison Example 5)
The steel sheet was plated with 36.0 g/m2 of nickel in the condition above-mentioned (l). Subsequently, this steel sheet was plated with nickel-phosphorus alloy ( nickel: 5.5 g/m2) in the condition above-mentioned (3). After that, the petroleum wax type lubricant shown in Table 1 was coated on the surface treated steel sheet. (Comparison Example 6)
The heat treatment and the temper rolling were practiced on a similar surface treated steel sheet to that of Comparative Example 5 in a similar condition to those of Example 12 to 14. After that, the petroleum wax type lubricant shown in Table 1 was coated on this steel sheet.
The ability of the continuous forming and the battery performance of the battery container were evaluated using the following method. The battery containers were manufactured from the surface treated steel sheet obtained in Example 1-14 and Comparative Example 1 to 6. The evaluation result was shown in Table 3 and Table 4 with the heating condition after forming.
(l) Evaluation of the ability of continuous forming of the battery container
The surface treated steel sheets for the battery container obtained in Example 1 to 14 and Comparison Example 1 to 6 was punched out into the blank. Then, the blank was continuously formed into a cylindrical container having 49.3 mm in the height and 13.8 mm in outside diameter using a drawing process (drawing speed: 50 containers/minute) consisting of eight steps.
After that, the upper edge portion was trimmed, and thus the battery container was completed.
The ability of continuous forming was evaluated by the standard shown as follows:
©: It was possible to continuously form more than 10000 containers without any scratches on the side wall of the container. O: It was possible to continuously form 5000-10000 containers without any scratches on the side wall of the container, but impossible to continuously form more than 10000 of them without causing scratches. A: It was possible to continuously form 2000 to 5000 containers with-

out any scratches on the side wall of the container, but impossible to continuously form more than 5000 of them without causing scratches. X : Many scratches frequently occurred on the side wall of the container, and less than 2000 containers could be continuously formed. (2) Evaluation of battery performance
The battery container that had been obtained by the method above-mentioned 1 was heat-treated in the condition in Table 3 and Table 4. The alkali manganese battery was manufactured from this battery container by the following method.
First, the manganese dioxide and the graphite were gathered at a rate of 10:1 by the weight ratio. Subsequently, the potassium hydroxide (8 moles) was mixed with this . Thus, the positive electrode mix was prepared. Then, the positive electrode mix was shaped into a fixed size doughnut type pellet by pressing in the metal mold. Next, this pellet was inserted and fixed in the obtained battery container with pressure. Next, in order to install the negative electrode plate that was spot-welded with the negative electrode collector rod in the battery container, the fixed position under opening edge of the battery container was processed in the neck-in. Next, the separator comprising the un-woven cloth made of the vinylon was inserted along the internal circumference of the pellet that was pressed into the battery container. Then, the negative electrode gel comprising the potassium hydroxide saturated with zinc granules and zinc oxide was inserted in the battery container. After, that, the negative electrode plate installed with the gasket of the insulating material was inserted in the

battery container followed by calking. Thus, the alkali manganese battery was completed. After this alkali manganese battery was left in the room temperature for 24 hours, the battery performance was measured. The battery performance was evaluated by two items which were the internal resistance values (m Q) by the alternating current impedance (frequency 1kHz) and short-circuit current values (A) at 1m Q. charge.
Both of the internal resistance value and the short-circuit current value were measured at the temperature of 20 °C. The evaluation results of the ability of the continuous forming of the battery container and the battery performance of them are shown in Table 3 and Table 4 with the heating condition of the battery container. The kind of petroleum wax type lubricant coated on the surface treated steel sheet is displayed in Table 1 and Table 2 using the following signs.
A: Paraffin wax
B: Micro crystalline wax
C: Liquid paraffin
D: Petrolatum
E: White petrolatum (Vaseline).
The overall evaluation in Table 3 and Table 4 is shown as follows: The one that is marked with © is excellent in the continuous forming of the battery container, and its internal resistance value is low, and its short-circuit current value is great. The one that is marked with O excellent in the continuous forming of the battery container, and is a little inferior in the battery performances but no problem on practi-
cal use. The one that is marked with X is inferior in either of the continuous forming of the battery container or the battery performance. The evaluation result in Table 3 and 4 is concluded as follows:
(1) Of the surface treated steel sheets for the battery container of
the present invention, that having the uppermost layer of nickel tin
alloy (Example 7 to 10) is more excellent in the battery performance
than that having a nickel based layer (Example 1 to 6) or that having
nickel-phosphorus alloy layer (Example 11 to 14).
(2) The reason why the battery performance of the nickel plated steel
sheet of Comparative Example 1 is inferior to the surface treated steel
sheet of Example 1 to 6 is that the amount of plated nickel is less. The
reason why the continuous forming ability of the battery container by
the surface treated steel sheet having a nickel based layer of Compara
tive Example 2 is inferior is that the coated petroleum wax type lubri
cant is less.
(3) The battery performance inferiority of the surface treated steel
sheet having nickel-tin alloy layer of Comparative Example 3 is due to
the metallic tin remaining on the surface, and a large amount of the pe
troleum wax type lubricant remaining on the obtained battery container
since the said lubricant was coated too much. The reason why the bat
tery performance of the surface treated steel sheet having nickel-tin
alloy layer of Comparative Example 4 is inferior is that the said lu
bricant remained although it was coated in a small amount since the
heating temperature of the obtained battery container was low.
(4) The surface treated steel sheet having nickel-phosphorus alloy

layer of Comparative Example 5 is inferior in the ability of continuous forming into the battery container, because the said lubricant was coated too little. Moreover, the heating duration of the obtained battery container was short, and the said lubricant remained, so that the battery performance is also inferior.
(5) As for the surface treated steel sheet having nickel-phosphorus alloy layer shown in Comparative Example 6, it is excellent in the ability of continuous forming into the battery container. Its battery performance is as good as those of Example 11 to 14. But, it was a case where the obtained battery container was heated for a long period of time. Such a case is undesirable in the viewpoint of the productivity of battery container and the cost reduction. For these examples and comparative examples, it is understood that the surface treated steel sheet for the battery container described in the claims of the present invention is more excellent in the continuous forming of the battery container. In addition, it is understood that the battery, that is manufactured from the battery container using said surface treated steel sheet after heating on the specified condition, has excellent battery performance.
( Table 1) State of obtained surface treated steel sheet

(Table Removed)
( Table 2 ) State of obtained surface treated steel sheet

(Table Removed)
( Table 3 ) The heating condition after formed into the battery container, and the evaluation result of the performance

(Table Removed)
( Table 4 ) The heating condition after formed into the battery container, and the characteristic evaluation result of the performance

(Table Removed)
( Effect of the invention )
It is possible to form the surface treated steel sheet for the battery container of the present invention more efficiently than the conventional one, wherein the blank and the metal mold must be coated with the lubricant in every container just before forming it into the battery container. It is also unnecessary degreasing the coated lubricant, rinsing and drying after forming into the battery container, which were essential in the past. The heat treatment just at the low temperature of 200 to 350°C can easily remove the majority of lubricants. This manufacturing method can efficiently produce batteries having excellent battery performance with reduced cost, so the industrial value is extremely high.
Summary
( objective ) A surface treated steel sheet for a battery container having excellent formability and battery performance and manufacturing method thereof are offered and the battery container using the said surface treated steel sheet is manufactured efficiently and at a low-cost.
( Solution ) First, the surface treated steel sheet, which is manufactured by plating after degreasing and pickling, or further heating after plating, is heated to the melting temperature of the petroleum wax type lubricant to be coated (Tm) to Tm+100°C. Next, the melted above-mentioned lubricant is coated to the surface. Then, this surface treated steel sheet is formed into the battery container by the deep drawing, the DI processing or the DS processing. After that, the steel sheet is heat-treated at the low temperature of 200 to 350°C.

WE CLAIM:
1. A method to produce surface-coated steel sheet for a battery container
comprising:
degreasing and pickling a steel sheet in a known manner, forming a surface coated layer by plating or further heat treatment after plating on said steel sheet in a known manner, and subsequently coating a thermally melted petroleum wax type lubricant layer on the surface of said coated steel sheet heated to the melting temperature of said petroleum wax type lubricant (Tm) to Tm + 100°C.
2. The method as claimed in claim 1, wherein said surface-coated layer
consists of either nickel plating layer or nickel-phosphorus alloy
plating layer, or two layers comprising both layers.
3. The method as claimed in claim 1, wherein said surface coated layer
is formed by plating nickel or nickel phosphorous alloy and tin on it,
and said heat treatment is in the air or in an non-oxidizing
atmosphere.
6. A method to produce surface-coated steel sheet for a battery container substantially as herein described with reference to and as illustrated in the foregoing examples.

Documents:

1821-del-1997-abstract.pdf

1821-del-1997-claims.pdf

1821-DEL-1997-Correspondence-Others.pdf

1821-DEL-1997-Correspondence-PO.pdf

1821-del-1997-description (complete).pdf

1821-del-1997-form-1.pdf

1821-del-1997-form-13.pdf

1821-del-1997-form-19.pdf

1821-del-1997-form-2.pdf

1821-del-1997-form-3.pdf

1821-del-1997-form-4.pdf

1821-del-1997-gpa.pdf

1821-DEL-1997-Petition-137.pdf

1821-DEL-1997-Petition-138.pdf

« Previous Patent

Next Patent »

Patent Number

197096

Indian Patent Application Number

1821/DEL/1997

PG Journal Number

51/2007

Publication Date

21-Dec-2007

Grant Date

14-Nov-2007

Date of Filing

01-Jul-1997

Name of Patentee

TOYO KOHAN CO., LTD.

Applicant Address

4-3, KASUMIGASEKI 1-CHOME, CHIYODA-KU, TOKYO 100, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	HITOSHI OHMURA	C/O TOYO KOHAN CO., LTD. KUDAMATSU-PLANT, 1302, HIGASHITOYOI, KUDAMATSU-SHI, YAMAGUSHI-KEN, JAPAN.
2	TATSUO TOMOMORI	C/O TOYO KOHAN CO., LTD. KUDAMATSU-PLANT, 1302, HIGASHITOYOI, KUDAMATSU-SHI, YAMAGUSHI-KEN, JAPAN.
3	HIDEO OHMURA	C/O TOYO KOHAN CO., LTD. KUDAMATSU-PLANT, 1302, HIGASHITOYOI, KUDAMATSU-SHI, YAMAGUSHI-KEN, JAPAN.
4	YUKIO NUMAMOTO	C/O TOYO KOHAN CO., LTD. KUDAMATSU-PLANT, 1302, HIGASHITOYOI, KUDAMATSU-SHI, YAMAGUSHI-KEN, JAPAN.

PCT International Classification Number

H01M 2/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA